1. Field Of The Invention
The present invention relates to a substrate processing apparatus and a substrate processing method, which supply a process liquid onto a surface of a substrate, such as a semiconductor substrate or an LCD substrate (a glass substrate for a liquid crystal display), so as to perform a predetermined substrate process, such as an application of a resist liquid or a development after exposure.
2. Description Of Related Art
In a manufacturing process of a semiconductor device and an LCD substrate, a resist pattern is formed on a substrate by a technique called photolithography. This technique is performed by a series of steps. Namely, a resist liquid is coated to a semiconductor wafer (hereinafter referred to as “wafer”), for example, so as to form a liquid film on a surface of the wafer. Then, the resist film is exposed by using a photomask, and thereafter the exposed resist film is developed, whereby a desired pattern is obtained
This process is performed by a resist-pattern forming apparatus generally formed by connecting an exposure apparatus to a coating and developing apparatus that coats a resist liquid and develops the same. As shown in FIG. 18, in this apparatus, wafers are transferred by a transfer arm 12 from a carrier 10, which accommodates therein a large number of wafers, to a processing part 1B. Within the processing part 1B, an anti-reflection film is formed in an anti-reflection film forming module (not shown), and a resist film is formed in a coating module 13. Thereafter, the wafers are transferred to an exposure apparatus 1D through an interface part 1C. The exposed wafers are returned again to the processing part 1B, and are subjected to a developing process in a developing module 14. After that, the wafers are returned to the original carrier 10. Before and after the process for forming an anti-reflection film and the process for forming a resist film, and before and after the developing process, the wafers are subjected to a heating process and a cooling process by heating modules and cooling modules, which are arranged at multiple levels in shelf modules 15a to 15c. 
In the processing part 1B, the wafers are transferred by main arms 16A and 16B between the respective modules. When the wafers are subjected to the aforementioned processes, a program has been previously made such that the wafers are transferred along a predetermined route. Namely, a transfer schedule, which determines, for all the wafers to be processed, transfer timings and modules to which the wafers are transferred, is stored in a memory. Thus, the wafers are transferred in accordance with the transfer schedule. A location on which the wafer is placed is referred to as “module”. In the transfer schedule, order numbers are allocated to the wafers, and transfer cycle data are chronologically arranged in which transfer cycles are specified based on a relationship between the order of the wafers and the order of the modules.
From the aspect of improving a throughput, a multi-module is usually set in the resist-pattern forming apparatus. The multi-module includes a plurality of modules that have the same transfer order, and perform the same process to wafers. There is a possibility that a certain module constituting the multi-module might become unavailable because of a trouble or lack of proper maintenance. A transfer of wafers in this case is proposed by Patent Document 1, for example. According to this method, a wafer to be transferred to the unavailable module is once transferred to a retraction module. Then, after another wafer has been processed in another available module constituting the multi-module, the wafer having been retracted to, the retraction module is transferred to the available module.
However, in order to improve a throughput, since the processing part 1B has been recently required to incorporate a large number of modules for processes, it becomes difficult to reserve a space in which the retraction module can be installed. In addition, in the multi-module, there is a possibility that a plurality of modules might be simultaneously subjected to a maintenance, such as an exchange of chemical liquids and a pump maintenance, and/or a nozzle trouble might be simultaneously occur in a plurality of modules. In order to cope with the case in which the plurality of modules become unavailable, it is necessary to prepare a plurality of retraction modules. However, it is difficult to reserve such a space.
It can be considered that a wafer is once retracted to a transfer stage, instead of the retraction module, which is incorporated in the transfer schedule. However, in this case, wafers cannot be transferred in accordance with the transfer cycles written in the transfer schedule, whereby the transfer of the wafers may be stopped or delayed. In this case, some wafers may stagnate in, for example, the heating modules, and the wafers may be overheated in the modules. Namely, a film quality is deteriorated, resulting in inferior wafers as products.
Patent Document 1: 3P2006-203003A (paragraphs 0037 to 0039)